【作者】 林琳；

【导师】 邵文柱；

【作者基本信息】 哈尔滨工业大学 ， 材料学， 2006， 硕士

【摘要】 本文研究了固溶处理对GH4169合金微观组织的影响,探讨了晶粒长大规律。通过热模拟试验,系统地研究了固溶淬火态GH4169合金的高温压缩变形行为,得出了流变应力与热变形参数之间的关系方程;采用金相、EBSD和TEM等分析手段,探讨了GH4169合金在高温变形过程中的微观组织演化规律,分析了热变形参数对动态再结晶体积分数的影响,同时,重点研究了预析出δ相对GH4169合金压缩变形行为的影响。对不同固溶处理条件下GH4169合金的微观组织观察结果表明,随着固溶温度的升高,δ相的数量逐渐减少并由短棒状向颗粒状转变,其完全溶解温度范围为1000~1050℃;合金的晶粒尺寸随固溶温度的升高和保温时间的延长而增大。低于δ相溶解温度固溶处理,δ相的存在会抑制晶粒长大,高于δ相溶解温度固溶处理,晶粒尺寸随固溶温度的升高快速长大。硬度测试结果表明,材料的硬度随固溶温度的升高和保温时间的延长而降低,硬度值与晶粒尺寸的关系符合H-P公式。对1100℃固溶淬火态GH4169合金的热模拟试验结果表明,动态再结晶是GH4169合金高温压缩变形过程中的重要软化机制;通过回归方法得到的该固溶淬火态GH4169合金的热变形激活能为472kJ/mol,压缩变形过程中流变应力与热变形参数之间的关系可用以下方程来描述:对GH4169合金热模拟试样的微观组织分析表明,动态再结晶的体积份数随变形温度的升高和应变速率的降低而增大,变形量的增加有助于动态再结晶过程趋于完全。研究发现,在实验变形条件范围内,固溶处理残余的δ相使GH4169合金高温变形的峰值应力降低。残余δ相含量为3.9%时,材料的热变形激活能减少至381kJ/mol。微观组织分析表明,在相同的变形条件下,固溶处理残余的δ相促进了GH4169合金动态再结晶过程的进行。更多还原

【Abstract】 This thesis studied the effect of solution treatment on the microstructure of the GH4169 alloy. And the hot deformation behavior of the GH4169 alloy has been studied by means of hot compression deformation tests. Based on the results of hot deformation tests, the relationship between the flow stress and the deformation parameters was obtained, which was characterized in the form of a constitutive equation. The microstructure evolution of the GH4169 alloy during hot deformation was analyzed by electron back-scattered diffraction (EBSD) technique, optical microscope and transmission electron microscope (TEM) observations. The dependence of the volume fraction of the dynamic recrystallized grain on the deformation parameters was also analyzed. Meanwhile, the influence of the hot deformation behavior of the GH4169 alloy on the remained delta phase was studied considering both mechanics behavior and microstructure evolution behavior.The microstructure observation results of the GH4169 alloy with different solution treatment processes show that the fraction of the delta phase decreases with the increase of the solution temperature, accompanied with a shape evolution from short rod to spheroid. The delta phases dissolve entirely in the temperature range of 1000~1050?C and the grain size of the GH4169 alloy increases with the increase of the solution temperature and holding time. The existence of delta phases restrains the growth of grain size when treated at temperatures below the complete dissolution temperature of the delta phase, while the grains grow quickly when heated above that of the delta phase.It can be concluded from the hardness testing results that the hardness of the GH4169 alloy decreases with the increase of solution temperature and holding time. The relationship between the hardness and the grain size conformed well with the Hall-Petch equation.Results of the thermal simulation tests for samples solution treated at 1100?C show that the dynamic recrystallization (DRX) is the main softening mechanism of the hot deformed GH4169 alloy. The activation energy (Q) of the GH4169 alloy is determined to be 472kJ/mol by the regression analysis method. The更多还原